Spacer primer cartridge for ammonium nitrate



Feb. 2, 1960 l D, E, ALBQN. EI'AL 2,923,238

SPACER PRIMER CARTRIDGE FOR AMMONIUM NITRATE v Filed May '7. 1957 2 Sheets-Sheet 1 ZMM Mz?" /4 rafa/Hx Feb. 2, 1960 D. E, ALBQN ErAL 2,923,238

SPACER PRIMER CARTRIDGE FOR AMMONIUM NITRATE FledrMay 7, 1957 2 Sheets-Sheet 2 5242/@ M/ff Arrow/[XII United States Patent 2,923,238 SPACER PRIMER CARTRIDGE FOR AMMONIUM NITRATE Dean Elliott Albon and John Frank Barco, Dn Quoin, Ill., assignors to Airmite-Midwest Incorporated, Du Qnoin, Ill., a corporation of Illinois Application May 7, 1957, Serial No. 657,692

2 Claims. (Cl. 102-22) The present invention relates to primer cartridges employed for the purpose of detonating ammonium nitrate and is concerned primarily with a spacer cartridge that is particularly designed for accurate centering in a cylindrical blast hole.

In the copending application of John Frank Barco and Dean Elliott Albon, Serial Number 642,215, tiled February 25, 1957 and entitled Primer for Ammonium Nitrate and Method of Using Same, there is disclosed a procedure under which a vertical blast hole is'loaded with an explosive charge comprising about 90% ammonium nitrate and 10% primer cartridge. The whole idea behind the method of this copending application is to so arrange the prilled or granulated ammonium nitrate with respect to the primer cartridge so that none of the ammonium nitrate is `located further from the primer cartridge a distance ranging from four to six inches. With such an arrangement, the ammonium nitrate is overdriven and has a rate of detonation comparable to that of the primer cartridge, whether Ait be dynamite or any other material employed for this purpose.

From the foregoing it is apparent that if the method of said copending application is to be properly carried out and the ammonium nitrate detonated with this over driving eect, the primer cartridge should be accurately centered in the blast hole.

With the foregoing conditions in mind, the present invention has in view as its foremost objective the provision of aprimer cartridge of the character aforesaid which is provided with means for accurately centering the same in a vertical cylindrical blast hole.

As explained in said copending application, the primer cartridge is ordinarily cylindrical and in accordance with the now prevailing conditions in strip mining operations, has a diameter of about 3" and is formed in sectional units, each of which has a length ranging from 12 to 16". Another object of the present invention is to provide a sectional unit of a primer cartridge which is readily adapted to having a spacer attachment applied to either end thereof.

In carrying out the above noted ideas in a practical embodiment, the present invention provides a primer cartridge unit consisting essentially of a cylindrical cardboard casing that is closed at one end by a thin metallic head that is crimped thereto and at the other end by an inverted cup-shaped cap. Extending between the head and cap is a tubular core which accommodates a primacord which may be knotted at one end to anchor that end to the lowermost of a plurality of such units when assembled. The spacer attachment is secured to the cupshaped cap.

Another highly important object of the invention is to provide ina primer cartridge unit of the character aforesaid, a spacer attachment which consists essentially of a central hub from which outstand a plurality of arms. The hub is received in and atixed to the cup-shaped cap and with the radially extending arms of the same length, the cartridge is centrally positioned in a blast hole.

inasmuch as it is impractical, if not impossible, to form a blast hole having a uniform cylindrical wall free of irregularities it is evident that with the arms of the spacer unit accurately dimensioned to conform to the diameter of the blast hole, considerable diiiiculty would be exnitrate, it is deemed preferable to arrange the lowermostv unit with the spacer attachment at the bottom of the hole. The next unit which is located immediately vthereabove is arranged with the spacer attachment at the top, and this is true of all other primer cartridge units which are included inthe charge.

Various other more detailed objects and advantages of the invention such as arise in connection with carrying out the above noted ideas in a practical embodiment will in part become apparent and in part be hereinafter stated as the description of the invention proceeds.

The invention therefore comprises a primer cartridge intended for use with ammonium nitrate which consists essentially of a plurality of sectional units 'each comprising a cylindrical casing with a head at one end, a cupshaped cap at the other, a tubular core extending between the head and the cap, a hub member received in and anchored to the cup-shaped cap and a plurality of radially extending arms outstanding from the hub member and having flexible end portions.

For a full and more complete understanding of the invention reference may be had to the following description and accompanying drawings wherein:

Figure 1 is a side view with parts broken away and shown in section of a primer cartridge sectional unit designed in accordance with the precepts of this invention;

Figure 2 is a top plan -view of the spacer attachment per se;

Figure 3 is a detailed diametric vertical section through one end of the unit taken on an enlarged scale;

Figure 4 is a detail of a portion of one of the radial arms showing the exible part in section;

Figure 5 is a perspective depicting the various elements of one of the units in exploded relation; and

Figure 6 is a vertical section of a blast hole showing the latter as loaded with ammonium nitrate using a primer cartridge made up of several sectional units of this invention.

Referring now to the drawings, one unit. of a sectional primer cartridge is shown as including a cylindrical casing 10. This casing is preferably of cardboard and when the cartridge is designed for use with blast holes having a diameter in the nature of 10 which is common practice in strip mining, the casing 10 will be of a diameter of about 3". Its length may range from 12 to 16".

At one end the casing 10 has crimped thereto a head or bottom 11 which may be of thin metal such as aluminum, and it is formed on its periphery with an annulal groove 12 which receives one end of the casing 10 and is crimped thereover. This head or bottom 11 is formed with a central aperture 13 that is defined by an inwardly extending ange 14.

The other end of the casing 10 is closed by a cup-shaped cap 15 having a peripheral flange 16 that is received il the bore of the casing 10 with a snug-tit. 'Ihe cup-shape: cap 15 is arranged so that it opens outwardly to present t recess defined by the ange 16.

A spacer attachment is referred to in its entirety by tht reference character A. The attachment A comprises a central hub made up of two wooden blocks 17 and 1l :h may be secured together in any preferred manner l as bythe nails shown at 19. The block 17 isdi- :sioned so that it is snugly and accurately received lin the cup-shaped cap 15. 'Ihe block 18 is somewhat er in diameter rand its peripheral edge extends slightly and the casing 10. These blocks 17 and 18 are formed i a truncated conical opening 20 with the larger end' ie opening being disposed inwardly.

he block 18 has a cylindrical surface 21 that is formed t a plurality of equi-angularly spaced sockets 22. In form of the invention illustrated in the drawings, four hese sockets 22 are formed in the block 18 but this lber could obviously be vari/ed without departing from spirit of the invention. Fitted in each socket 22 with essed fit is a rod 23 which preferably is of wood and :h extends outwardly from the block 18. Fitted over end of each rod 23 is a flexible coil spring 24. Thus,

l arm which extends radially outwardly from the hub 18 is made up of a rod 23 and a exible section 24.

iously, these arms should all be of substantially the e length.

he cup-shaped cap 15 is formed with acentral aper- 25 that is defined by an outwardly extending flange 26. s aperture 25 is in alignment with the aperture 13 in head or bottom 11. A tubular core 27 is vfitted in the tures 13 and 25 and is preferably received within the ges 14 and 26 with a pressed fit. At one end the 27 projects outwardly into the opening 20 formed in blocks 17 andgl8. This tubular core 27 together'with opening 20 accommodates a primacord that is shown nte and a primer cartridge made up of several units of invention will be described.

geological formation is represented at 30 and is vn as being formed with a vertical blast hole 31 :h as pointed out above will ordinarily have a diamof about 10". This blast hole31 has a bottom at 32. :ralof the-units of this invention are'first assembled so the spacer attachment A on one of the units will be rst to enter the hole and a primacord 28 is passed ugh the tubular core 27. A knot 33 is formed in the As shown in Figure 1,v the casing 10 is filled withan apby-step overdriving effect may be obtained from the primacord to the primer cartridge and thence to the ammonium nitrate. Thus, with the ammonium nitrate having the lowest rate of detonation, the commercial dynamite'3`6 a higher rate and the primacord 28 a still higher speed of detonation, when the primacord 28 is detonated the dynamite 36 will be detonated and overdriven to achieve a speed of detonation greater than it would ordinarily exhibit. This increased rate of detonation of the dynamite is transmitted to the ammonium nitrate as the latter is overdriven. Thus, the ultimate effect is achieved of detonating the ammonium nitrate at a rate .comparable to the speed of detonation of the primacord.

While a'preferred specific embodiment of the invention is hereinbefore set forth it is to be clearly understood that the invention is not to be limited to the exact dimensions,

constructions and materials illustrated and described because various modifications of these details may be pro` vided in putting the invention into practice within the purview of the appended claims.

.What is claimed is:

1. In a sectional primer cartridge, a unit comprising a l cylindrical cardboard casing adapted t3 contain a detonating explosive, a metallic head crimpedv to one end of said casing and formed with a central opening, a cup-shaped metallic cap fitted in the'other end of said casing and formed with a central opening, a tubular core received in v block secured to` said first block and'h'aving a diameter greaterthan that of said casing', saidblocks being formed with aligned openings in alignment with said tubular core,

said second block having a peripheral surface formed witha plurality of angularly spaced sockets, and a radial arm received in each of said sockets.

2. In a sectional primer cartridge, a unit comprising a cylindrical cardboard casing adapted to contain a detonating explosive, a metallic head crimped to one end lof said casing and formed with a central opening, a cup-shaped metallic cap fitted in the other end of said casing and a spacer attachment received in and secured to said cupfor anchoring purposes. 'I'he other units are now 1g on the cord 28so that the spacer attachment A is 1e top of each of such units. .The cartridge comprisv these several units'strung on the primacord 28 is then :red into the blast hole 31, which action isreadily itated by the flexible end sections 24 of the radially nding arms. When the attachment A reaches the bot- 32 of the hole, thevan'ous units making up the car- ;e will be accurately centered. Prilled or granulated ionium nitrate such as represented at 34 is now .'ed into the hole 31 about the primer cartridge and tol ace of about 4" above the uppermost unitof such a ridge. Stemming, represented at35, is then applied to he hole and confnethe explosive charge. The prishaped cap, said attachment comprising a circular block y snugly received in said cap, a second larger circular block ord 28 extends upwardly through the stemming and secured to said first block and having a diameter greater than that of said casing, said blocks being formed with aligned openings in alignment with'said tubular core, said second block having la peripheral surface.v formed with a plurality of angularly spaced sockets,` a rod received in each of said sockets, and a flexible coil spring carried at the free end of each of said rods, `each rod and spring constituting a `radial arm with all of said radial arms of substantially the same length.

References Cited in the tile `of this patent UNITED STATES PATENTS 710,323 Hatfield Sept. 30, 1902 1,560,815 Hill Nov. 10, 1925 2,195,871 Kuster Apr. 2, 1940 2,305,729 Ne Dec. 22, 1942 2,362,829 Kinley ...f Nov. 14, 1944 2,516,041 Abrams July 18, 1950 2,706,949 Kessenich Apr. 26, 1955 2,733,658 Moat ...A Feb. 7, 1956 2,775,200 Guenter Dec. 25, 1956 

